Tweak the Zero to not power through USB3

#1

HI !
I’m a regular user of SBC and for my work i took the liberty to buy a Radxa Zero which could perfectly fit in the project i work on.
I’m using a USB3 Camera - FLIR Blackfly S and i require a good bandwidth, that’s why i bought this SBC.
Thing is, this Camera is powered externally. I only want the board to retrieve the infos and not powering up the camera.
The board is currently running Armbian last stable release.
Tried a dmesg but i got in loop : “Maybe the USB Cable is bad ?” , which is not because i got it working on my Arch computer with the same cable and no issues there.
I tried to swap the USB3 Micro B cable for a regular USB 2 cable and the camera worked great but i’m limited by the bandwith of USB2 and i don’t want that.

Could you please enlighten me or give me any tips on how to tweak the board to think that the Zero should not power USB3 but only use data transmissions.

I’ll gladly appreciate any help ! :grinning:

#2

Hello, you didn’t really describe what’s not working or how you came to believe it’s a power problem. Could you post all the dmesg output after connecting the camera?

Anyway, I think you can work around power problems by putting a powered hub in between the device and host, because then the device has to negotiate with the hub… I think. Since your camera is already powered, you might not need to power the hub externally.

I had trouble with an old Zaurus, when its USB OTG port in host mode was severely limited in its power budget so that I sometimes could not even attach a particular mouse or a joystick. (it didn’t suffer brown outs-- it simply refused to initialize because the device claimed to require XX mA, and that was too much.) With a cheap hub and a 5V supply, I was even able to use a 2.5" hard disk on a USB adapter, which needed quite a bit more power just to spin up. But that was a USB 2.0 hub on a USB 1.1 host, so… YMMV

#3

Hi,
Thxs for the answer, i’ll try to be more clear in the following.

I have a USB3 Camera equipped with a USB3 MicroB port that i use for data transmission, and an Hirose connector for trigger and power.

The camera is powered at all time through the Hirose port.

When i connect the USB3 cable to a computer, dmesg would normally return the following

2022-10-18T10%3A52%3A31%2C537296111%2002%3A00
2022-10-18T10:52:31,537296111 02:00.png925×169 31.2 KB
file:///home/aleroux/2022-10-18T10:52:31,537296111+02:00.png

When i connect the USB3 cable to the Zero, dmesg return these errors in loop

2022-10-18T10%3A48%3A26%2C766410278%2002%3A00
2022-10-18T10:48:26,766410278 02:00.png772×119 20.9 KB
file:///home/aleroux/2022-10-18T10:48:26,766410278+02:00.png

But when i switch the USB3 Type A to MicroB of the camera with a USB 2.0 micro which is the basic part of the MicroB connection, the camera is detected like it should by the Zero and i can get frames, see dmesg

2022-10-18T10%3A51%3A02%2C209991358%2002%3A00
2022-10-18T10:51:02,209991358 02:00.png918×157 28.5 KB
file:///home/aleroux/2022-10-18T10:51:02,209991358+02:00.png

That’s why i’m thinking it’s a power problem with the USB 3 host on the Zero.
I’m using the USB3 Host port of the Zero which can go up to 5 Gbps of bandwidth, the one with OTG like you mentionned, i only use it for powering up the card, so it shouldn’t cause any issue no ? The camera has a maximum power consumption of 3W and it’s taken care of by the external power supply. Funny thing, when i power the camera only with the USB connector and when i use a USB 2.0 cable, the camera works great too. At maximum the camera requires 600 mA if used with USB only.

I can’t see why it’s working with USB 2.0 but not with USB 3 on the same port and in the same conditions.

I’ll try soon with a power supplied usb hub, when i receive one and i’ll be in touch with you on that part.

Antoine

#4

Thanks for clarifying. Unfortunately, some of the search results for that error message seem to be from people having trouble with hubs. Their problems are not necessarily the same problem, but it still might be a waste of time.

USB 3.0+ connections use three differential pairs in the cable for data, while earlier versions have only one. That’s how it achieves significantly higher bandwidth (close to SATA which uses two pairs). If any of the 4 lines for those 2 extra pairs was damaged or not functioning, a USB 2.0 connection would still work on the same port because it would have nothing to do with those lines and of course nothing connected to them. I don’t know exactly how the USB 3 subsystem typically reacts to bad connections, but your error seems to be it… also, it apparently didn’t say anything about power. So, as your cable is known to be good, it seems your Zero might be damaged or defective. Have you tried any other USB 3.0 devices? I’m sorry-- that is officially “USB 3.1 Gen1” now, because insanity

#5

Yeah, first thing i’ve done was to look on the net for that particular problem but as you said it’s mostly for issues with hubs.

Thanks for explaining that part.

Right now this camera is the only USB 3.1 Gen1 aka USB 3 :wink: device i have. I tried with some USB 3 devices like USB key or HDD/SSD and it’s working great. For an NVMe SSD connected to the Zero, i got a read speed of 190 MB/s which seems okay for the bandwidth range of 3.1 Gen1 no ? Or am i reading this wrong ?
If i’m reading this correctly, i should be able to at least read the camera state because USB 3 connection seems to work, but it isn’t the case.
In two days, i’m gonna receive a powered usb hub and i’ll try with it. I’ll keep you informed on that part.

#6

Hey there !
I tried with a powered hub, the same problem occurs, but !
I tried using a very short cable (typically the ones used for usb 3 hdd) and it’s working great now.
I think the main cause comes from the cable length. Don’t know why it’s working with shorts ones (~ 20-30 cm) but not with longer cables (3m - 4m). Maybe the signal can’t get to the board because of the distance and it’s too weak ?!
And i got great speeds, not the speed i expected but it’s fine (mostly around 2 Gbps).

So my problem is solved now, but it should be written somewhere on that forum that the Zero doesn’t like long cable with USB 3 Host port. So if somebody in the future have a issue with USB 3 connection like the one i had, please consider trying with a short cable :wink: